3d micro-curved epitaxial structure and preparation method

Abstract

A 3D micro-curved epitaxial functional structure comprises a base layer that includes, from bottom to top, at least a sapphire substrate layer and a first epitaxial layer. A mask layer is located above the base layer, with spaced grooves that extend through it and expose the upper surface of the base layer. Multiple 3D micro-curved epitaxial structural units are formed, each with its bottom part filling a corresponding groove and its upper surface exhibiting a smooth 3D curved structure. Each 3D micro-curved epitaxial structural unit is partially in contact with the upper surface of the mask layer. By introducing an excess of Ga source while adjusting the crystal plane orientation angle during wet etching with Sc source, multiple epitaxial growth processes are performed to form the 3D micro-curved epitaxial functional structure, achieving compatibility with chip epitaxial processes and providing technical feasibility for creating complex structures.

What is claimed: 
     
         1 . A method for preparing a three-dimensional (3D) micro-curved epitaxial functional structure, comprising:
 step S1 of providing a base layer, which comprises at least a sapphire substrate layer and a first epitaxial layer in order from bottom to top;   step S2 of growing a mask layer above the base layer;   step S3 of dry etching the mask layer to form spaced grooves, wherein the grooves penetrate through the mask layer and have their bottoms positioned on the upper surface of the base layer, to obtain a sample;   step S4 of placing the sample into a reactor, and introducing hydrogen (H 2 ), ammonia (NH 3 ), nitrogen (N 2 ), a scandium (Sc) source, and an excess Ga source under a temperature range of 400° C. to 900° C. to grow 3D micro-curved epitaxial structural units;   step S5 of performing photolithography on the 3D micro-curved epitaxial structural units to define an area to be etched;   step S6 of wet etching the area to be etched to form a structure comprising one polar plane F 3  and two semi-polar planes F 1 ;   step S7 of repeating steps S4 to S6;   wherein a Ga source flow rate is 10,000 sccm to 100,000 sccm, an H 2  flow rate is 50 L/min to 100 L/min, an NH 3  flow rate is 50 L/min to 100 L/min, and a N 2  flow rate is 50 L/min to 150 L/min; and   a curvature of the 3D micro-curved epitaxial structural units is 1000R to 1800R.   
     
     
         2 . The method according to  claim 1 , further comprising: introducing an aluminum (Al) source, wherein a flow rate of the Al source is 50 sccm to 1000 sccm, and a molar molecular weight ratio of the Al source is 5% to 90%. 
     
     
         3 . The method according to  claim 1 , wherein the step S7 is repeated 3 to 10 times. 
     
     
         4 . The method according to  claim 3 , further comprising: growing an additional functional layer on the outer surface of the 3D micro-curved epitaxial structural unit, wherein the additional functional layer and the 3D micro-curved epitaxial structural unit form a heterojunction superlattice multi-quantum well structure layer or a channel layer. 
     
     
         5 . The method according to  claim 1 , wherein a molar molecular weight ratio of the Sc source is 5% to 30%. 
     
     
         6 . A three-dimensional (3D) micro-curved epitaxial functional structure, comprising:
 a base layer, which includes at least a sapphire substrate layer and a first epitaxial layer, arranged sequentially from bottom to top;   a mask layer located above the base layer;   the mask layer provided with grooves distributed at intervals, wherein the grooves penetrate the mask layer and expose the upper surface of the base layer;   a plurality of 3D micro-curved epitaxial structural units, wherein a bottom part of each of the plurality of 3D micro-curved epitaxial structural units is filled with the corresponding groove, and an upper surface is a smooth 3D micro-curved structure, and each of the plurality of 3D micro-curved epitaxial structural units is in contact with the upper surface of the mask layer.   
     
     
         7 . The 3D micro-curved epitaxial functional structure according to  claim 6 , wherein the mask layer is AlN or SiN, and each of the plurality of the 3D micro-curved epitaxial structural units is made of ScGaN or ScAlGaN and its superlattice structure. 
     
     
         8 . The 3D micro-curved epitaxial functional structure according to  claim 6 , further comprising an additional functional layer that covers each of the plurality of the 3D micro-curved epitaxial structural units and forms a heterojunction superlattice multi-quantum well structure or channel layer with the each of the plurality of 3D micro-curved epitaxial structural units. 
     
     
         9 . The 3D micro-curved epitaxial functional structure according to  claim 6 , wherein the vertical height of each of the plurality of the 3D micro-curved epitaxial structural units from the bottom of the groove to the top of the upper surface is 1 μm to 7 μm. 
     
     
         10 . The method according to  claim 1 , wherein after Metal-organic Chemical Vapor Deposition (MOCVD) epitaxial growth in the reactor and subsequent etching, an original polar plane F 3  is transformed into a new structure comprising one polar plane F 3  and two semi-polar planes F 1 , and similarly, an original semi-polar plane F 1  is also transformed, after MOCVD epitaxial growth and etching, into a new structure comprising two semi-polar planes F 1  and one polar plane F 3 , until a smooth upper surface of the 3D micro-curved epitaxial structural units is achieved, thereby obtaining the 3D micro-curved epitaxial functional structure.